Why does each end of a muscle need to attach different bone?

Muscles attach to bones by way of tendons. Each end of a muscle needs to attach to a different bone so that the muscle can generate movement and create tension. When a muscle contracts, it pulls the bone that it is attached to closer to the other bone. This movement creates tension in the muscle and allows the body to move. If both ends of a muscle were attached to the same bone, the muscle would not be able to generate any movement because there would be no tension created.